Compensator



Dec. 15, 1936. w PlERCE 2,063,947

COMPENSATOR Filed Aug. 8, 1953 17106775237 George (1). Fierce (Litorfleg Patented Dec. 15,1936

. NITE STATES PATENT OFFICE 25 Claims.

The present invention relates to vibratory systems and apparatus, and more particularly to electrical systems and apparatus employing electromechanical vibrators, such as are dis- 5 closed in a copending application, Serial No.

678,482, filed June 30, 1933. From a more limited aspect, the invention relates to the transmission and reception of intelligence, using sound waves as the agency ,of communication, and to means for directively discriminating a sound beam. The term sound will be employed hereinafter, in the specification and the claims, to include the supersonic, as well as the audible, part of the sound spectrum, and to include also all kinds of elastic vibrations. The invention, indeed, finds particulanapplication to supersonic communication.

The primary object of the invention is to provide a new and improved compensator for the Z0 transmission and reception of sound in any selected direction.

A further object of the invention is to provide a directionally selective transducer or transceiver of soundfor submarine communication and di- 35 motion finding.

Another object is to provide a new and improved system for directively discriminating a sound beam.

Other and further objects will be explained to hereinafter, and will be particularly pointed out in the appended claims.

The invention will now be explained in connection with the accompanying drawing, in which Fig. 1 is a diagrammatic view illustrating 5 one application of the invention; and Figs. 2 and 3 are similar views of modifications.

Referring first to Fig. 1, let the straight'line I 82 represent a diaphragm in the form, say of a plate, disposed in communication with a sound- L0 conducting medium, such as air, or the ocean, for the purpose of propagating therein, or receiving therefrom, signal sound (including supersonic) waves. Acoustic energy is thus interchanged between the medium and the diaphragm. =5 Thesound beam has high-pressure points, and

low-pressure points. The position of the highpressure and low-pressure points will, of course, depend on the wave length. Neighboring high and. low-'pres'sure points will be a half-wave- 0 lengthapart.

The diaphragm may be turned to an angle 0 with a line 4 passing through the lower end of the diaphragm I82, and extending at right angles to the direction of an incoming beam of signal sound waves, traveling in the direction indicated bythe arrow I83. The angle 0 is thus the angle between the plane wave front and the plate diaphragm I82 on which the wave front is incident. At this particular angle 0, the impinge- 0 ment of the sound beam upon the diaphragm I82 will thus cause a periodic displacement of the parts of the diaphragm, in the manner described as a standing wave, as explained in a copending ap lication, Serial No. 591,838, filed February 9, 1932. The periodic impulses of pres- 5 sure of the sound wave will all strike the highpressure points of the diaphragm in the same phase, say a. push. The rarified impulses will similarly all strike the diaphragm at the lowpressure points in phase, say a pull. Consequently, they will exert forces upon the diaphragm of such a nature as to tend to bend the diaphragm into an undulating form.

Cumulative interaction is, therefore, produced between the vibrations of the segments of the gieaphragm I82 and the vibrations of the sound With a given, properly designed plate-diaphragm, there is, for each of a large number of selected frequencies, a particular angle 6. of maximum response.

The signal will, therefore, be detected if the diaphragm I82 is disposed to the sound beam at the proper angle 0, which will be the angle of maximum response for the particular frequency of the signal. If the diaphragm is turned away from that angle 0, the pressure impulses will strike it with a distribution which is improper to produce resonance in the diaphragm. The vibrations in the diaphragm will then be much smaller than at the particular angle 0 that produced resonance. The term "resonance is here used to denote cumulative reinforcement of the vibration of the diaphragm by the incident sound.

As the diaphragm occupies a given angle corresponding to resonant response to the sound beam, it is possible to determine the'direction of the sound beam; and as departure from the angle associated with resonance carries with it non-resonance, it is possible to obtain a very 40 sharp determination of direction.

There are two positions of maximum response of the plate I82, on opposite sides of the normal, and each corresponding to an angle 0 between the plate I82 and the wave-front (or between the direction of propagation of the sound and the normal to the plate). Waves from either of the symmetrical directions I83 and I83 excite the plate in cumulative resonance. A pointer'l88 or other index mechanically coupled to the plate I82 60 and reading on a suitable angular scale (not shown) may be used to measure the angular position of plate I82. The direction of the sound source will be along the line bisecting the angle between the two positions of the pointer at "which maximum response is obtained.

It is possible to operate the system at a single frequency of signal, even if such frequency is but one component of a source of noise containing many frequencies. All that is necessary is to tune the angle of maximum response. sound arrival with respect to the position of the plate I82, at maximum response, and with repoints.

the hereinafter-mentioned amplifier to the required frequency and to turn the diaphragm to The angle of spect to the selected frequency of the sound beam, is known from the constants of the instrument, as explained more fully in the said application, Serial No. 591,838;

The diaphragm I82, whether a plate, cone, or

of some other form, as described in the said -application, Serial No. 591,838, may be mounted by aflixing it to a rigid support at any of its nodal Inasmuch, however, as the nodal points occur at different places for different frequencies,

it may sometimes be preferable to mount the diaphragm on rubber or some other cushioning ma-.

diaphragm, and the mechanical vibrations thus.

produced in the wire are transmitted along the wire, with the velocity of sound in the metal, to the other end or some other point of the wire.

There, they are converted into electrical energy, which may be put to any desired use. Conversely, the vibrations may be excited electrically, mechanically or otherwise, at the said other end of the wire and transmitted, along the wire, to the diaphragm at the first-named end, and radiated from the diaphragm out into space, as through the water of the'ocean; for, as the operation is completely reversible, the same apparatus ofsthe inventionis equally applicable to sending as to receiving.

If the diaphragm is to be used at one frequency only, as for directive reception or radiation of The wire cores I6 to 23 may be of nickel, nickelsteel, nickel-copper, nickel-cobalt, chrome-nickel, chrome steel, or of any'other metal element or alloy characterized by comparatively large magnetostrictive: effects. The, use of a number of wires also renders it possible to transform' the vibrational energy into electrical energy more efiiciently. The terminals of the coil I86 may be connected to the tunedamplifier of a receiver or to an oscillator (either of which is indicated at 42) for receiving or sending purposes, respectively. In case a plurality of coils are used, as, for example, the coils I94 of-Fig. 3, they may be connected either in series or parallel to the amplifier or oscillator 42. These wires may be used to conduct the sound waves thus produced from the multiple take-off points to a single, common, sound-detecting converter I86 of sound into electric energy.

The converter I86 is shown as a pick-up coil, to a which the wire cores I6 to, 23 are magnetostrictively coupled, so as to obtain electric current or:

voltage from the mechanical vibrations of the cores I6 to 23, or vice versa. The voltage or-current developed may be fed from, orinto, the oscil-,

vibration in the wires 56 to 23, and may be of any desired type, such, for example, as is illus- Letters Patent 19,461, issued February 12, 1935.

Polarizing magnets (not shown) may be employed in connection with the magnetostrictive wires I6 to 23 or, preferably, the polarizing field trated and described in United States Reissue may be obtained by passing a direct current through the pick-up coil 186.

The oscillator or receiver 42 is tuned, as by means of tuning condensers (not shown), to the same frequency as the frequency of the soundbeam signal, or to a desired component of the sound frequency.

, The device may thus be used for directive discrimin'ation' of an incident sound beam coming in the directon of the arrow I83, using the plate diaphragm I82 disposedat an angle 0 with a line at right angles to the direction of the beam, vi-

brating in segments as a standing-wave system,

as described above. As is stated in the said application, Serial No. 591,838; if V0 is the velocity of sound in the medium, such as air or water, and

, V is the velocity .of propagation 'of elastic waves inthe material of the diaphragm I82, then V sm 0- V V The incidence of, say, a pressure peak of the wave front on the plate diaphragm I82, at the lowermost point of the plate diaphragm shown in Fig. 1 will, as before stated, produce a bending of the plate, and this disturbance will be propagated along the plate I82 to the other, or upper, end thereof, with a velocity determined by the constants of the diaphragm and the frequency.

The explanation of the phenomenon described in the opening paragraph of this specification may now be made in mathematical terms.

If the angle 0 is such that the transverse vibration in the plate diaphragm I82 produced by the incident sound wave at the sin 0= -1owermost-point (Fig. 1) will arrive at the opposite end of the plate I82, or at any intermediate point along the plate, at the same instant that the pressure peak-of the incident sound wave which .originatedit, travelingin the medium with a dent wave in the medium. This is what is meant I by the statement that, at this particular angle 0, the vibrations of the plate 2 are in resonance with the vibrations in the sound beam in the medium.

Again, with the system of multiple take-off wires, a diaphragm can be constructed which will receive or transmit sound along one direction only, namely, the normal to the plate. All that is necessary is to construct a plate in which the velocity of propagation of transverse vibration is very low, and in which transverse vibrations are g 2,068,947 ,mon rubber diaphragm I 82, or in any other suitable Way, as illustrated in Fig. 2. Under these conditions, each wire I8 to 28 will pick up and transmit vibrations from the incident sound independently, but if the various receiving elements are not situated in the same region (or similar regions) of pressure of the incident wave, the various impulses at the transformation apparatus will not be inthe same phase, if the wires be of the same length, and the net signal will be less than if all the separate impulses be made to add in phase. Signals arriving in any oblique direction, as indicated by the arrow I88, will give less effect thanthose arriving in the normal direction, as indicated by the arrow 8I2.

The 'wlres'iit' to 28 are shown in plan view only,

so that they appear to be of different lengths.

or differing by even multiples of a wavelength if it is desired that the equally phased vibrations originating at the ends remote from the coil I88 shall arrive at the coil I88 in phase.-

. The metallic diaphragms I to 8 are provided with their faces lying in a plane and along a line of length suflicient, in relation to the wave length of sound in the medium, to give sharp directional .discrimination. The spacing between centers of adjacent diaphragms I to 8 should not be greater than one half -wavelength of sound in the medium at the highest frequency to be employed. Otherwise the compensator will have multiple angles of response.

' The diaphragms I to 8 may be fewer or more in number than'illustrated, and maybe of any de-. sired form. The sound is radiated to or from the diaphragms I to. 8, the magnetostrictive cores I8 to 23 that drive them, or that are driven by them,

' being secured thereto. For reception and trans mission of'aounds of any desiredfrequency. par- .ticularly high frequencies, through the water or J other elastic media, the diaphragms I to 8 will be submerged in the ocean. According to the preferredarrangement, thediaphragms I to 8 are shown disposed side by side, but out of contact with one another, at uniform intervals along a I substantially? straight line, attached to the comtransmit or receive most efiiciently in the plane of the paper, it will be necessary to give the array'of diaphragms I to 8 a dimension perpendicular to the plane of the paper large in comparison with I the wave length employed. Corresponding units of the lineanarrays should then be joined by sound conducting'wirs, of equal length, to the appropriateretarding wires I8 to 23.

A composite, acoustic-energy converter is thus I provided, having a large number of diaphragms I to 8, all separated frorn one another, yet all free to vibrate to produce a common, enhanced effect. In reception, assuming, for example, a beam of particular, high-frequency sound, modulated or unmodulated, below and to the right 'of Fig. 2, the incidentsound beam, directed, for example, from,

"a distant sending station (not shown) at an angle to the line of diaphragms I to 8, located at a The invention finds also as range finding.

receiving station, such as a ship, will impinge on the diaphragms I to 8 in numerical order, beginning with the lowermost diaphragm I. The diaphragm's will all become excited into vibration, in numerical sequence. Mechanical vibrations will, first, begin to travel along the lowermost wire I8, connected with the lowermost diaphragm I, toward the coil I88, before they do so in the next lowermost wire I'I, connected with the next diaphragm 2, and so on. By the time that the sound impulse has reached the uppermost diaphragm 8, the mechanical vibrations will have traveled along the wire I8 a predetermined distance, along the next'wire IT a smaller distance, along the wire I8 9. still smaller distance, and so on. The wires I8 ting a particular, selected frequency of mechanical vibration. If the lengths of the wires I8 to 23 are so adjusted that the mechanical vibrations, traveling along the wires, shall be so retarded as to reach the coil I88 at the same moment, the efiects will reinforce one another, and the coil I88 will operate upon all the wires I8 to 23, in synchronism, to convert their mechanical vibrations, by magnetostrlction, into electrical energy, thereby to produce an enhanced eflect as to intensity.

The sound impulses will thus add together at the coil I88, positioned to receive this signal as a maximum, and convert it into an electrical voltage which is fed into the receiver 42. Sound impulses from other sources, having a different orientation with regard to the array, will arrive out of phase ,with each other at the coil I88 or very weak combined maximum response to a given direction of the sound beam in the medium, it is possible to deto'28 thus serve as retardation wires for transmittermine the direction of the sound beam; and as departure from the said angle carries with it a smaller degree of response, it is possible to obtain a very sharp determination of direction. many other uses, such If the diaphragms I to 8 are arrangedait equal intervals along a straight line, the inclination of which to the sound beam, will vary with the direction of the sound beam to be transmitted or received, the sound waves will, of course, arrive at the diaphragms at successive, equal time intervals apart. In reception, for example, the angle of the line' of diaphragmsd to 8 should be such that they shall receive the sound in phase. If the-sound happens to be incident normal to the array of diaphragms I to'8, the apparatus a number of sound receivers I to 8 are thus r I v.

delayed in such manner as to bring all the separate impulses together at a common listening point at the same instant. From the period of 'delay introduced in each of the various lines, the angle of incidence of the sound is determined. Compensating devices have heretofore been operat'ed at low, audible frequencies, and the retardation has been introduced, for example, electrically, or by means of speaking tubes of variable lengths. The present invention deals with new and improved apparatus, employing wires or other cores as sound conductors for obtaining the desired retardations. Longitudinal sound vibrations in these wires travel with constant velocity from the terminal unit I (say) to the coil I86, and the time retardation introduced in each of these wires, therefore, is directly proportional to the length of wire lying between the diaphragm I and the coil I86. In sending, it is particularly desirable to have a large number of diaphragms in an extended array whose dimensions are large in comparison withv the wave length used, in order to radiate power essentially in a beam of sound. Whether receiving or sending, the. diaphragms should be so arranged as to operate in phase if it is-desired that soundl'be received or radiated along a line perpendicular to the array of diaphragms.

If it is desired to locate the direction of a sound source without rotating the vibratory member I82, it is possible to do so by altering the lengths of the sound paths from the device to the transformation apparatus to compensate for the difference in phase at the vibrator. may be-done in a number of wa s, of which one is shown in Fig. 3. The diaphra s 9, to, II and I2 may be permanently fixed in position and may operate without the necessity of bodily rotation. H

Coils I94 are shown in Fig. 3 mounted on a rotatable arm I96 equipped with the pointer I96 for the purpose of varying proportionately the distances along the sound-conducting wires I92 of the coils from the pick-up units, and thus'introducing proper retardation of the sound arriving at the coils to compensate for lags in the time of arrival of the soundrat the pick-up units, thereby to bring the sound to all the coils in the same phase. With the coils as shown in Fig. 3 parallel to the line ,of the pick-upunits, the lengths of the wires I92 intervening between the coils and their associated pick-up units should all be made equal, so that sound arriving at the pickup units in the direction of the normal. to the array and, therefore, in same phase, will undergo equal retardation in all the wires I92 and, consequently, arrive at the coils I94 in the same phase. of their proper positioning to take advantage of the various cooperative effects of the vibrator .,wires- I92.

Alternatively, therefore, all the wires (of equal lengths) may be brought .out together and surrounded by a single coil I86, as illustrated in Figs. 1 and 2, or connected with separate coils I94, as in Fig. 3.

It is very important, in any type of phase compensator, to prevent reflections of energy from the ends of the retardation lines. In other Words, sound energy passing by the coil I86 or I94, and arriving-at the end of the wire, must not be allowed to reflect and return a second time to the coil. If this occurs, a standing wave sys- 4 tem is set up in the wire and the net result is The arrangement of the coils permits sounds from one direction only, responds equally to sounds arriving from two directions making equal angles with the normal to the array of diaphragms on both sides of the normal. There should be no standing waves at the points where the take-oil" coils I86 and I94 are located for, in a standing-wave system, the nodes and loops are fixed in space. In order to get rid of standing waves, the wave reflected from the end of the wire must be eliminated in some way. This may be done by making the free ends of the wires I6 to 23 and I92 long, so that any wave which passes the coil travels a long path before returning to the coil I86 or I94, by reflection, and is thereby diminished by the natural attenuation along the wire. This attenuation may be increased, however, by wrapping the wire tightly in some damping substance, such as rubber or felt, and the necessary free length thus reduced. I I have found it c0nvenient, however, to prevent such reflection by enclosing the free ends of the wires I6 to 23 and I92 tightly in a soft rubber sleeve 34 a foot or so in length, which absorbs and dissipates any sound energy reaching it.

The invention finds many uses; among them, owing to its directive discrimination of sound beams,direction finding. As the diaphragm occupies a given angle corresponding to resonant response to the sound beam, it is possible to determine the direction of the sound beam; and as of submarine sounds (such as the revolving pro-.

peller of boats or submarines), through the agency of the high-frequency componentsof these sounds. I have found that a noise, as of a ship, an airplane propeller or exhaust, or escaping steam or air, has high-frequency components of considerable intensity. Such a sound may be located asto direction by a device tuned, or selective as to frequency, with a sensitive range at 20, 30, 40 or 100 kilocycles, or any other value, so that the highly directive action of receivers such as the present receiver, operating at supersonic, or'other .high frequency, may be utilized in locating sound sources that are ordinarily explored by their audible pitches.

' Modifications will obviously occur to persons skilled in the. art, and all such are considered to fall within the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

. 1. Apparatus of the character described comprising a plurality of smal independently vibrating members mechanically coupled to and positioned in a. sound-conveying medium for cumulatively interacting with a sound beam in the medium, the vibrators being disposed inthe medium in the form of a plane array, means for magnetostrictively interconverting electricand mechanical energy, and a plurality of independent, magnetostrictive, sound-transmitting means connecting the vibrators with the interconverting means, the lengths of the sound-transmitting means being such that the length of the sound paths thereover from the vibrators to the interconverting means shall compensate for the difference in phase at the vibrators.

2. A system for the directive discrimination of a sound beam having a predetermined direction in a sound-conveying medium having a diaphragm vibratory in segments and disposed in the medium at an angle to the sound beam such that a transverse vibration propagated along the diaphragm has a velocity component, in the said predetermined direction, equal to the velocity of the beam in the medium, whereby cumulative interaction is produced between the vibrations of the segments and the vibrations of the beam, means for converting the vibrations of the diaphragm into electric energy,comprising a plurality of independent sound-transmitting vibrators of magnetostrictive material aifixed at spaced points on the diaphragm, and means magnetostrictively' cooperative with the vibrators, the lengths of the vibrators being such that the length of the sound paths thereover between the diaphragm and the cooperative means shall compensate for the phase differences at spaced points on the diaphragm of a transverse vibration propagated in the diaphragm.

3. A system for the directive discrimination of a sound beam having a predetermined direction in a sound-conveying medium having a diaphragm vibratory in segments and disposed in the medium at an angle to the sound beam such that a transverse vibration propagated along the diaphragm has a velocity component, in the said predetermined direction, equal to the velocity of the beam in the medium, whereby cumulative interaction is produced between the vibrations of the segments and the" vibrations of the beam, and a plurality of converting devices comprising a plurality of coils and a plurality of sound-transmitting magnetostrictive wires, the coils being adjustable along their respective transmitting wires.

4. Apparatus of the character described comprising a diaphragm, a magnetostrictive core connected with' the diaphragm, a movable coil for the core, and means for moving the coil along the core.

5. Apparatus of the character described comprising a plurality of diaphragms, a vibratory sound-transmitting, magnetostrictive core connected with each diaphragm, and a common coil for and magnetostrictively cooperative with the cores, the cores being of lengths such that the length of the sound paths thereover between the diaphragins and the coil shall compensate for phase differences of sound at the diaphragm to produce phase equalization at the common coil.

6. Apparatus of the character described having, in combination, a diaphragm, and a magnetostrictive converter of sound energy into electro-magnetic energy comprising a plurality of magnetostrictive take-off wires afiixed at spaced points on the diaphragm, and a coil magnetostrictively cooperative with the wires, the lengths of the wires being such that the length of the sound paths thereover between the diaphragm and the coil shall compensate for the phase differences at said spaced points on the diaphragm of a transverse vibration propagated in the diaphragm.

7. Apparatus of the character described comprising a plurality of diaphragms in a plane array disposable at any angle with a sound beam in a medium, a plurality of sound-transmitting magnetostrictive wires attached thereto, and a plurality of coils cooperating each with one of said wires for interconverting sound and electric energy, the lengths of the wires between the coils and the diaphragms being adjustable so that differences of phase at the several diaphragms of the sound waves in the medium can be compensated or produced, and a rotatable carrier upon which the coils are arranged so that, by rotation of the carrier, the phase relation between electro-magnetic energy in the, coils and sonic energy at the diaphragm may be varied.

8. Apparatus for the directive discrimination of a sound beam in a medium comprising a vibratory diaphragm, and a magnetostrictive con:- verter of sound energy into electromagnetic energy comprising a plurality of magnetostrictive take-off wires aifixed at uniformly spaced points on the diaphragm, and a coil magnetostrictively cooperative with the wires, the wires being of lengths such that the length of the sound paths thereover between the diaphragm and the coil shall compensate for the phase differences at said spaced points on the diaphragm.

9. Apparatus for the directive discrimination of a' sound beam in a medium comprising a vibratory diaphragm, and a converter of sound into electricity, said converter comprising a plurality of magnetostrictive take-off wires afiixed at spaced points of the diaphragm, and coil means magnetostrictively cooperative with the wires, the wires being of lengths such that the length of the sound paths thereover between the diaphragm and the coil means shall compensate for vibrational phase difierences at said spaced points on the diaphragm.

10. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a plurality of transducers adapted to be positioned in a sound-conveying medium in which the phase of vibration of the sound is progressively different from transducer to transducer, a magnetostrictive core affixed in sound-communicating relation to each transducer, an adjustable coil magnetostrictively cooperative with each core, each of said cores being adapted to transmit sound vibrations along its length at a predetermined velocity to enable each core and its associated coil to cooperate to introduce a predetermined phase difference between each transducer and its corresponding coil, and means for simultaneously adjusting the coils along their corresponding cores to predetermined positions such that, owing to the time of travel of the sound vibrations along the cores between each transducer and its corresponding coil, vibration peaks which occur at the same instant of time at the predetermined positions occur at the said progressively difierent times at the corresponding transducers, whereby the said progressive differences in phase of vibration of the sound from transducer to transducer is compensated for or produced by the progressively difierent times of travel in the said cores between the transducers and their corresponding coils.

11. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a plurality of transducers adapted to be positioned in a sound-conveying medium in which the phase of vibration of the sound is progressively difierent from transducer to transducer, a magnetostrictive core affixed in sound-communicating relation to each transducer, an adjustable coil magnetostrictively cooperative with each core, the coils being dispo ed. along a substantially straight line, each vibrations along j its length at a predetermined velocityitq enable"each core and its associated coillto lcooperate to introduce a predetermined relation. to predetermined positions such that,

owing to the time of travel of the sound vibrations along the cores between each transducer and its corresponding coil, vibration peaks which occur. at thesame instant of time at the predetermined positions occur at the said progressively different times at the corresponding transducers, whereby the said progressive differences in phase of vibration of the sound from transducer to transducer is compensated for or produced by the progressively different times of travel in the said cores between the transducers and their corresponding coils.

12. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a plurality of transducers adapted to be positioned in a sound-conveying medium to transmit sound energy into the medium, a magnetostrictive core afiixed in soundcommunicating relation to each transducer, an adjustable coil magnetostrictively cooperative with each core for magnetostrictively converting electromagnetic energy into sound energy, each of said cores being adapted to transmit the resulting sound vibrations along its length at a predeterminedvelocity to the corresponding transducer, and means for simultaneously adjusting the coils along their corresponding cores to predetermined positions such that, owing to the time of travel of the sound vibrations along the cores between each coil and its corresponding transducer, and the phase differences introduced thereby in the respective cores by the retardation of the sound energy, sounds that are in phase at the predetermined positions are caused to reach the transducers in a predetermined phase relation such that the sound will travel from the transducers into the sound-conveying medium in the form of a sound beam having a predetermined direction.

13. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a plurality of transducers adapted to be positioned in a sound-conveying medium to receive the energy of a sound beam traveling in the said medium along a predetermined direction, a magnetostrictive core afiixed in sound-communicating relation to each transducer, an adjustable coil magnetostrictively cooperative with each core and in which voltage is 'magnetostrictively produced by sound vibrations in the core, whereby each core will'transmit the sound energy received by the corresponding transducer to the corresponding coil, and means for simultaneously adjusting the coils along their corresponding cores to predetermined positions such that, owing to difierences in the time of travel of the sound vibrations along the said cores between each transducer and its corresponding coil, and to the phase corrections introduced thereby in the respective cores, the voltages in the several coils will be in phase.

14. Means for interchanging sound energy of any phase in a medium and electromagneticenergy of any other phase, comprising a sound conducting core, magnetostrictive means for interconverting electromagnetic energy and vibrationa1 energy in the core at a first predetermined point ofi s aid 1 adapted to transmit sound on the core, means for interconverting sound energy in the medium and vibrational energy in the core at a second predetermined point on the core, whereby the phase relation between said sound energy in the medium and said electromagnetic energy is determined by the linear distance along the core between said first predetermined point and said second predetermined point on the core, and means for relatively adjusting the core and the magnetostrictive interconverting means.

15. Apparatus for interchanging sound energy of any phase in a medium and electromagnetic energy of any other phase, comprising a vibratory diaphragm coupled to the medium, a sound-conducting core of magnetostrictive material afiixed thereto, a winding axially positioned on the core for magnetostrictively interchanging electromagnetic energy in the coil and vibrational energy in the core, and means for adjusting the distance along the core between the diaphragm and the coil, whereby the relative phases of the vibrational energy at the diaphragm and the electromagnetic energy in the coil are controllable.

16. Apparatus for interconverting electromagnetic energy of any phase and sound energy of any difierent phase comprising a linearly disposed magnetostrictive vibrator along which the sound energy may be transmitted, means for varying the length of the transmission path in the vibrator to produce the phase difference by the retardation of the sound in traveling the said varied length of the path, and coil means magnetostric tively cooperative with the vibrator for converting the energy.

17. Apparatus for the directive discrimination of a sound beam in a medium comprising, in combination, a diaphragm transversely vibratory and with dimensions large in comparison with the wavelength of transverse vibrations in the diaphragm, said diaphragm being angularly posi tionable relative to the sound beam and characterized by a maximum of interconversion of vibratory energy in the diaphragm and acoustic energy in the medium when disposed at an angle 0 to the beam such that sin 0=% where Vo=the velocity of the sound beam in the medium, and V=the velocity of transverse vibrations in the diaphragm, a sound-conducting core aifixed to the diaphragm for conducting vibrations between the diaphragm and a relatively distant point on the core, means comprising a coil magnetostrictively cooperative with a portion of said sound-conducting core and situated at said relatively distant point for interconverting electromagnetic energy and vibrational energy in the core, and means for relatively adjusting the core and the coil.

18. Apparatus for the directive discrimination of a sound beam in a medium comprising, in combination, a diaphragm transversely vibratory and with dimensions large in comparison with the wavelength of transverse vibrations in the diaphragm, said diaphragm being angularly positionable relative to the sound beam and characterized by a maximum of interconversion of vibratory energy in the diaphragm and acoustic energy in the medium when disposed at an angle 6 to the beam such that sin 0- where Vo=the velocity of the sound beam in the medium, and V=the velocity of transverse vibrations in the diaphragm, a plurality of sound-conducting cores of unequal lengths affixed to points of unequal vibrational phase on the diaphragm,

and magnetostrictive means for interconverting electromagnetic energy and vibrational energy at preselected points on the cores, the lengths of the cores between the diaphragm and the said preselected points being such as to compensate, by difierences of time of travel of sound energy along the several cores, for the inequality of phase of vibration at the points of aflixment of the cores to the diaphragm.

19. Apparatus or the character described comprising a diaphragm disposable at any angle with respect to a sound beam, a plurality of devices for converting sound into electric energy or vice versa and comprising a plurality of coils and a plurality of sound-transmitting magnetostrictive wires at riably positioned points to vary the lengths of said vibrators efiective as transmission paths between the variably positioned points and the corresponding fixed points and thereby to introduce phaseretardation differences in the said respective vibrators by the varied retardation of the sound energy in traveling said varied lengths of the vibrators, and means disposed at thevariably positioned points 'and cooperative with the said vibrators magnetostrictively to convert the energy at the said variably positioned points.

21. Apparatus for interchanging electro-magnetic energy and sound energy comprising a plurality' of sound-transmitting, magnetostrictive vibrators through each of which sound vibrations may be transmitted at a predetermined velocity to introduce a predetermined phase retardation, each vibrator terminating in a fixed point positioned in a sound-conveying medium in which the phase of vibration of the sound is progressively different from fixedpoint to fixed point and each extending to a second point, and magnetostrictive-coil means positioned at the second point, the vibrators having effective transmissionpath lengths such that, owing to the time of travel of the sound vibrations along the said vibrators, vibration peaks which occur at difierent instants of time at the said fixed points of the vibrators occur at substantially the same instant of time at the second point on each of the vibrators, whereby the said progressive differences in phase of ibration of the sound from fixed point to fixed point is compensated for by progressively different phase retardations along the said vibrators, the magnetostrictive-coil means being adapted to interact with the vibrators to convert the energy.

22. Apparatus of the character described comprising adiaphragm', 'a magnetostrictive core one end of which is connected with the diaphragm, a movable coil magnetostrictively cooperative with the core, whereby mechanical vibrations magnetostrictively produced in the core through the action of an electric current in the coil will be mechanically transmitted along the core in both directions from the position occupied by the coil, or whereby mechanical vibrations in the diaphragm will be mechanically transmitted along the core irom the position occupied by the diaphragm tov and beyond the position occupied by the coil, means for moving the coil along the core, and means for damping the other end of the core along a region of the core equal in length to several wavelengths of the said mechanical vibrations to prevent reflection of vibrational stresses in the corefrom the said other end of the core.

23. Apparatus of the character described comprising a diaphragm, a magnetostrictive core one end ofrwhich is connected with the diaphragm, a movable coil magnetostrictively cooperative with the core, whereby mechanical vibrations magnetostrictively produced in the core through the action of-an electric current inthe coil will be me-' chanically transmitted along the core in both directions from the position occupied by the coil, or whereby mechanical vibrations in the diaphragm will be mechanically transmitted along the core from the position occupied by the diaphragm to and beyond the position occupied by the coil, means for moving the coil along the core, and a tube of vibrational-energy-absorbing material in which the other end of the core is tightly enclosed along a region of the core equal in length to several wavelengths of the said mechanical vibrations to dampthe core to prevent reflection of vibrational stresses in the core from the said other end of the core.

24. Apparatus of the character described comprising a plurality of transducers at a plurality of alined points, a plurality of magnetostrictive cores, one end of each core being connected in sound-communicating relation with one of the transducers, a movable coil magnetostrictively cooperative with each core, means for simultaneously adjusting the coils to cause them to assume predetermined positions with respect to the corresponding cores, and means for damping the other ends of the cores.

25. Apparatus for magnetostrictively interchanging electromagnetic energy and sound energy having, in combination, a plurality of transducers adapted to be positioned in a sound-conveying medium and to cooperate directionally for intercommunicating energy with the medium by variably phased elastic mechanical vibrations, a plurality of magnetostrictive cores, one end of each core being afiixed in sound-communicating relation to each transducer, a movable coil magnetostrictively cooperative with each core, each of said cores being adapted to transmit vibrational stresses along its length at a definite velocity to enable each core and its associated coil to cooperate tointroduce a predetermined phase displacement between transducer and coil, means for simultaneously adjusting the coils to predetermined positions along the several cores to enable the combination of coils, cores and transducers, by introducing predetermined and interdependent phase retardations of the said vibrational stresses in the several cores, to cooperate directionally, and means for damping the other ends of the cores.

GEORGE W. PIERCE. 

